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Neutron Scattering Upgrades at the High Flux Isotope Reactor

Neutron Scattering Upgrades at the High Flux Isotope Reactor. James B. Roberto Associate Laboratory Director Oak Ridge National Laboratory presentation to Basic Energy Sciences Advisory Committee Gaithersburg, Maryland July 22, 2002. Outline. HFIR update Neutron scattering upgrades

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Neutron Scattering Upgrades at the High Flux Isotope Reactor

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  1. Neutron Scattering Upgrades at theHigh Flux Isotope Reactor James B. Roberto Associate Laboratory Director Oak Ridge National Laboratory presentation to Basic Energy Sciences Advisory Committee Gaithersburg, Maryland July 22, 2002

  2. Outline • HFIR update • Neutron scattering upgrades • Beam lines and shielding • Cold source • New and upgraded instruments • User program

  3. New reflector, cage, and shroud installed New cooling tower completed New process waste line installed Larger beam tubes fabricated and installed Improvements to electrical, mechanical, and control systems SAR and TSR updates completed and approved Operational Readiness Review completed Operations resumed in December 2001 A major refurbishment has been completed at HFIR Installing the new reflector New cooling tower

  4. Neutron scattering upgrades • New guide hall • New and upgraded instruments • Cold source intensity comparable to the world’s best • Increased thermal neutron intensities • Formal user program (same as SNS) The upgraded HFIR will include 15 state-of-the-art instruments on some of the world’s most intense steady-state neutron beams

  5. Larger beam tubes for increased intensity using vertical focusing Shielding tunnel at HB-2 to support multiple beams/instruments New shutter assemblies and monochromator drums to support larger, more intense beams Beam lines and shielding New monochromator drum New HB-2 beam tube with beryllium inserts

  6. Beam tube installation

  7. Installation of the HB-2 shielding tunnel Shutter assembly Shield blocks

  8. Refrigerator plant completed Moderator vessel completed Neutron guides in fabrication New instruments (SANS I & II) in fabrication SANS hall under construction (includes increased user support space) Cold source update The HFIR cold source will have a brightness comparable to the best in the world

  9. Cold source and guide systems Refrigerator Cold-source moderator vessel Cold neutron guide Compressors Guide Hall

  10. Cold Instruments Thermal Instruments CG-1 CG-2 CG-3 CG-4A CG-4B CG-4C CG-4D *Proposed Cold triple-axis spectrometer* 40-m high-resolution SANS 35-m biology SANS USANS Reflectometer Cold triple-axis spectrometer (U.S./Japan) SNS optics test station HB-1 HB-1A HB-2A HB-2B HB-2C HB-2D HB-3 HB-3A Polarized triple-axis spectrometer Fixed energy triple-axis spectrometer Powder diffractometer Residual stress diffractometer Wide angle neutron diffractometer (U.S./Japan) Triple-axis spectrometer Triple-axis spectrometer Four-circle diffractometer Instrument suite after upgrades • Improved optics, monochromators,and software • Thermal neutron intensities increased 2-10 times at sample position • Cold neutron intensities increased 100 times for SANS • New guide hall with expanded user support space

  11. Thermal neutron triple-axis spectrometers • HB1A: Ames/ORNL (installation in October) • Fixed incident energy at 14.7 meV • World class for magnetic structures • HB1: Installed, running in commissioning mode • Standard or fully polarized mode • Excellent for magnetic excitations, magnetic structure, and phonons • World class for polarized inelastic studies • HB2: Installation Spring 2003 • High-intensity thermal beams for incident energies up to 45 meV • World class for medium energy excitations in small or weakly scattering samples • HB3: Installation in October • Versatile thermal instrument for unpolarized measurements • World class for medium- and high-resolution inelastic scattering at thermal energies HB-1 schematic

  12. HB-1 triple-axis spectrometer upgrade • Installed and operating in commissioning mode • New monochromator drum and instrument shutter • New software, display, motor configuration, and analyzer wedge system • New vertically-focused monochromator • Typical intensities at sample 3 times higher • Similar improvements at HB-2 and HB-3

  13. HB-3 triple-axis spectrometer staged for installation

  14. Neutron powder diffractometer upgrade Addition of 12 new detectors, bringing total to 44 Vertically focusing monochromator using individually-deformed Ge wafers • New software, diffractometer control, and sample environments • Factor of 10 performance improvement for most experiments • World class for structural studies, magnetic structures, texture and phase analysis

  15. High-intensity powder diffractometer for time-resolved studies and diffuse scattering (U.S./Japan instrument) New monochromator system Detector being overhauled New instrument controls Factor of 5-10 gain in intensity World class for single-crystal diffuse scattering and time-resolved powder studies Wide angle neutron diffractometer upgrade

  16. Four-circle diffractometer upgrade • New monochromator (vertically focused, bent stacks of thin perfect crystals) • New diffractometer control system • New software for more efficient peak searching using 7-anode detector • Factor of 2-4 performance improvement • World class for small unit-cell crystal structural studies, particularly H-bonding

  17. Cold-neutron triple-axis spectrometry • High-resolution measurements of excitations • Many frontier problems in condensed matter and other areas demand these instruments • Highly correlated electronic systems • Quantum magnetism • Molecular and nanocluster magnetic systems • Frustrated and random systems • Superconductors Field dependence of excitations in a spin-gap system

  18. Cold triple-axis spectrometers at HFIR • CG-4C: U.S./Japan spectrometer (in progress) • Cold triple-axis based on BNL H4M instrument • Vertically focusing monochromator • CG-1: STAR - Sub-thermal Triple-Axis Research Spectrometer (proposed) • Incident energies up to 25 meV • Harmonics removed by velocity selector • Vertically diverging “trumpet” guide allows enhanced vertical focusing • Polarized beam measurements • World class for high-resolution measurements of excitations in single crystals – complementary to time-of-flight instruments

  19. STAR at various wavelengths and mosaic spreads 0.4˚ 1.4•108 1.9•108 8.8•106 0.8˚ 1.3•108 1.6•108 6.4•106 1.2˚ 1.1•108 1.2•108 4.7•106 1.8 Å (25 meV) 3.0 Å (9 meV) 6.0 Å (2.3 meV) Comparison with other instruments: NG0 calc* (Broholm) 7•107 1.2•108 7•107 8•106 IN14 (40´ coll) 3.5•107 2.0•107 6•106 RITA (open) 3.5•107 2.8•107 SPINS (40´ coll) 4•106 2.4 Å (14 meV) 3.0 Å (9 meV) 4.0 Å (5 meV) 6.0 Å (2.3 meV) Calculated flux at sample position for CG-1 (STAR) Assumptions: 2C guides (horizontal & vertical), “ideal” vertical focusing, perfect peak reflectivity, incident collimation 40´. CG-1 has both high intensity and good Q resolution. * NG0 or MACS has a large double focusing monochromator with low Q resolution in this configuration

  20. Cold neutron spectrometers for large-scale structures • Cold Neutron Reflectometer (MIRROR) • Length scales 3 < L < 3000 Å and reflectivities to 5 x 10-8 • World class for interface and thin-film structure and dynamics, protein adsorption and bio-film and complex fluid structure at surfaces, semiconductor and metallic multilayers, etc. • 40-m High-Resolution Small Angle Neutron Scattering Spectrometer (SANS) • 2-D large area (1m2) detector, ~106 Hz count rate • Wavelength 5 <  < 30 Å (∆  /  = 5-12%) • World class for high-resolution kinetic studies of phase separation in polymer blends and metallic alloys, small (~1mm3) crystals, and new directions in soft materials (e.g., in-situ processing) • 35-m Medium-Resolution (Biology) SANS (OBER) • 2-D large area (1m2) detector, ~106 Hz count rate • Wavelength 6 <  < 30 Å (∆  /  = 9-28%) • World class for studies of weakly scattering bio-materials, small samples (~1 mg), and pharmaceuticals and developmental polymers available only in small amounts

  21. Reflectometer upgrade • Moving to a cold beam line in the guide hall • Factor of 10 increase in flux • Factor of 10 decrease in background • 100X more sensitive • Protein adsorption and bio-film structure at surfaces • Semiconductor and metallic multilayers • Polymeric segregation and bio-molecular diffusion • Complex fluid structure at surfaces • Time evolution of these surface structures

  22. Small Angle Neutron Scattering Flux increases of two orders of magnitude and larger (2.5x) area detectors will make it possible to: • Explore new directions in soft materials such as in-situ processing using a neutron beam to follow structure evolution in industrially relevant equipment (e.g., extruders, flow devices) • Study weakly scattering biological materials (cross sections 10-1-10-3 cm-1) • Use much smaller samples (1mg vs. 100mg) • Pharmaceuticals and developmental polymers available only in small amounts • Biological materials, which are often difficult to prepare in bulk • Small (~1mm3) crystals of high-Tc superconductors for flux line lattice melting • Undertake kinetic studies (e.g., phase separation kinetics in polymer blends and metallic alloys) • Use polarized neutrons to explore magnetic materials, super-paramagnetism, spin-glasses, etc. SANS I and II include 1m2 2-dimensional area detectors

  23. Comparison of SANS facilities ( = 10Å )

  24. User program schedule • A few experienced users can be accommodated immediately • Planning for the formal user program is under way with SNS (written user plan being prepared) • A general call will be made in the fall (formal user program starts at the end of the calendar year) • Instruments will be phased into the user program as they are commissioned (5-6 instruments by early 2003, 10-12 in early 2004)

  25. HFIR user program guiding principles • Reliable, predictable operation (>220 days/year at >90% schedule predictability) • World-class instrumentation • Fully staffed user support • Formal proposal review system with external committees • Integrated HFIR/SNS user program • HFIR/SNS users group (provide input for instrumentation and user operation)

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